Z1000A1 carbs, mixture screw

[scott]

Mixture screw under the carb……is it turn in to richen mixture? Or does turning it in make it weaker?

[KeithZ1R]

Fuel screw in to weaken Air screw out

[scott]

Thanks. I can’t seem to find where exactly it states that in the manual. It does state 11/2 turns out but doesn’t seem to define which way riches or weakens. Colourtune it shall be then.

[warren3200gt]

Thanks. I can’t seem to find where exactly it states that in the manual. It does state 11/2 turns out but doesn’t seem to define which way riches or weakens. Colourtune it shall be then.

One and a half turns sounds like an airscrew on side of carb setting.
Under the bowl fuel screw setting is 0.75 to 1 turn out.
Airscrew is in to richen.
Fuel screw is out to richen.

[Kev1R]

Carbs on my 1978 A2 have a screw mounted centrally and underneath the carb. This is a fuel screw, but confusingly referred to in the Kawasaki manual as a mixture screw. On my bike they have to be 1 1/4 turns out or it will not pull cleanly,
My 1978 Z1r was different as it had an air screw in the side of each carb.
Good luck!

[scott]

Same as my 1978 A2 with A1 carbs Kev. As Warren states, fuel screw out to richen then.

[scott]

Can anyone tell me where in the manual it states fuel screw out to richen, what page etc

[KeithZ1R]

Scott whilst that specific instruction isnt actually used ,, look at page 136, cutaway drawing H6 Pilot system and it becomes pretty apparent what the effect of adjusting either way is

how ever to allay your fears here is a little research



In carburetors, the air screw and fuel screw (also called pilot screw) both affect the air-fuel mixture at idle, but they do so in different ways. The air screw controls the amount of air entering the pilot circuit, while the fuel screw regulates the amount of fuel. Generally, on the air intake side of the carburetor, it's an air screw, and on the engine side, it's a fuel screw.
Here's a more detailed explanation:
Air Screw:

Location: Typically found on the air intake side of the carburetor, closer to the air filter.

Function: Adjusts the amount of air that mixes with fuel in the pilot circuit.
Effect:

Turning it in (clockwise) reduces air flow, richening the mixture .

Turning it out (counterclockwise) increases air flow, leaning the mixture .

Fuel Screw:

Location: Typically found on the engine side of the carburetor, closer to the engine.

Function: Adjusts the amount of fuel that mixes with air in the pilot circuit.
Effect:

Turning it in (clockwise) reduces fuel flow, leaning the mixture .

Turning it out (counterclockwise) increases fuel flow, richening the mixture .

Key Differences:

Effect on Airflow: The air screw directly controls the airflow into the pilot circuit, while the fuel screw controls the fuel flow.

Location: Their position on the carburetor helps determine which screw is which.
Impact on Mixture: Both screws affect the air-fuel mixture, but the air screw primarily does so by controlling the air component, and the fuel screw by controlling the fuel component.

Where is my air/fuel screw? : r/motorcycles
In essence, if you are adjusting the mixture at idle, understanding whether you are adjusting air or fuel flow is crucial for proper carburetor tuning.

[warren3200gt]

They probably don't mention it in the fsm as originally there was a cap that fitted over the fuel screw to deter fiddlers

[Kev1R]

I think this is Keith's diagram - "a picture paints a thousand words"
And gives another name for the screw as 'pilot screw'

fuel screw.jpg (61.67 KiB) Viewed 375 times

[scott]

Thanks guys